Flat panel display (FPD) technology is one of the fastest growing display technologies in the world, with a potential to surpass and replace cathode ray tubes (CRTs) in the near future. As a result of this growth, a large variety of FPDs exist, which range from very small virtual reality eye tools to large hang-on-the-wall television displays.
The FPD generally includes a hermetically sealed vacuum container or envelope formed by sealing an anode substrate to a cathode substrate. A display employs phosphors at pixel locations which emit light when energized.
The anode substrate and the cathode substrate of such displays are made of thin glass plates each having a thickness as small as, for example, between 0.5 to 2.5 millimeters (mm) and are spaced from each other at a distance as small as 0.2 mm, resulting in the envelope being highly reduced in thickness. The substrates are rectangular and each of the same size. The substrates can be any size. Viewing areas vary accordingly and can be used as automotive, telephone, computer and other displays requiring small (or large) size and high (or low) resolution and larger sizes for computer and television devices, for example. However, the attachment of devices to insure the evacuation of residual gases in the envelope often compromise the overall thickness of the construction. U.S. Pat. No. 6,084,344 ('344 patent) issued on Jul. 4, 2000 to T. Kishino et al. and entitled “Reduced Thickness Vacuum Container With Getter” and assigned to Futaba Denshi Kogyo K.K. of Japan, describes prior art techniques used to evacuate such displays having anode and cathode substrates. The patent also describes a problem which is inherent in making thin displays. For example, as indicated above, such displays may have a spacing as small as 0.2 millimeters. The evacuation tube which goes to the evacuation pump has an inside diameter which is approximately 2 mm and an outside diameter of 4 mm. Therefore, since the evacuation tube has a diameter (outside) of 4 mm, one cannot easily evacuate the display via the thin bonded sides or the periphery, which sides are bonded by a glass frit joining the anode plate (or substrate) to the cathode plate. This cannot be done because of the fact that if the glass is, for example 0.7 mm in thickness, the entire display including the spacing is about 1.6 millimeters in thickness (0.7 mm cathode+0.7 mm anode+0.2 mm spacing). Therefore, the tube from the pump is of a diameter greater than the thickness of the display. The above-noted '344 patent discloses a first series of solutions that involve putting a through-hole in the cathode or the anode substrate with no hole in the periphery. When placing a hole or aperture in the periphery of the display one had to extend the anode or cathode structure so that one could place a getter box over the display, which getter box as shown in FIG. 8 and FIG. 9 of the '344 patent has an aperture including an internal cavity which contained a getter, and which getter box interfaced with the side surface of the display. In any event, in order to support the getter box, one had to extend either the cathode or the anode plates. This is clearly shown in FIGS. 8, 9, 10 and 11 of the '344 patent. FIGS. 12 and 13 of the '344 patent also show apertures in the periphery of the device, with the aperture communicating with the getter box, which again requires an extension of either the cathode or the anode. In that patent, the evacuation is always transverse to the cathode and anode plates thereby significantly increasing the thickness. In order to insure that the FPD functions reliably, the envelope formed by the anode and cathode must be evacuated of all gases. Typical evacuation is in a range between 10−5 and 10−6 Torr so that the displays emit electrons with great efficiency. However, one can see also from the above noted patent, this creates a problem and requires extending the anode or cathode substrate to accommodate the getter box.
The present invention involves placing a getter box at the sides or periphery of the display, which getter box is attached to the periphery of the display without the need to extend the cathode or anode substrate.